Boattail without boattailing

[Gone2]

Is there a way to boattail a small sedan without doing a full on boattail?

[spacer]

Mount a force field generator in the trunk, and tweak the "shell" until it's about the right shape. Another effect is that the tailgater who doesn't stop in time may be vaporized by the field, but that's his own fault, right?

[CigaR007]

I have been pondering an inflatable decklid extension for my Toyota Echo sedan. It could be controlled manually by a switch or automatically depending on vehicle speed. That way, it is less imposing (size-wise) when deployed and easily hidden when not needed. I believe that would be a good compromise and yield interesting results.

Here is what my car should look like when fully done !

[Gone2]

I think I will remove the bumper and turn it into a pan that flows to the trunk. I may shave the edge of the trunk lid down a little and see about shaving the sides of the car. I don't mind doing the boattail, just seeing if there were any other options.

[duffremle]

I've kind of wondered about the feasibility of a windsock style boattail. Something along the lines of a sea anchor, but fitted to the rear end of the car with just enough of an opening to fill it with air at speed.

[aerohead]

Originally Posted by Sentraguy

Is there a way to boattail a small sedan without doing a full on boattail?

Kamm and Korff recommended cars with enough boat-tail such that the wake would be 1/2 the frontal area of the vehicle.That occurs at about 50% of aft-body boat-tail.Thie recommendation is based on 'practical' length for operating in traffic,negotiating streets,turns,curbs,ramps and parking.
Your design drag coefficient will determine how much you add.
I looked over my materials and it looks like a car with 'no' aft-body streamlining at all would be limited to a Cd minimum of 0.20.An extreme example would be the Blue Flame rocket powered land speed record car.It's rocket ship body has a higher drag than the blunt and 'stubby' Renault Vesta II.
It would basically be impossible to achieve lower drag without extending the rear.

[KamperBob]

Originally Posted by aerohead

Kamm and Korff recommended cars with enough boat-tail such that the wake would be 1/2 the frontal area of the vehicle.That occurs at about 50% of aft-body boat-tail.Thie recommendation is based on 'practical' length for operating in traffic,negotiating streets,turns,curbs,ramps and parking.
Your design drag coefficient will determine how much you add.
I looked over my materials and it looks like a car with 'no' aft-body streamlining at all would be limited to a Cd minimum of 0.20.An extreme example would be the Blue Flame rocket powered land speed record car.It's rocket ship body has a higher drag than the blunt and 'stubby' Renault Vesta II.
It would basically be impossible to achieve lower drag without extending the rear.

Half wake sounds pragmatic.

[Sven7]

Originally Posted by duffremle

I've kind of wondered about the feasibility of a windsock style boattail. Something along the lines of a sea anchor, but fitted to the rear end of the car with just enough of an opening to fill it with air at speed.

Wouldn't this work like a parachute, sucking energy from the car?

Here's how I see it. To inflate the sock it would have to have at least equal pressure inside than out. This would mean it's got to pull in a lot of air. So, to keep it from deflating or rippling at speed it might add more drag to your car than it actually solves. If you closed off the back and had small intakes at the cant rails like a Ford RS200's air intakes you might be able to keep it inflated. But I still doubt the real-world viability. Venturi intakes, perhaps?

[Gone2]

I noticed today as the cold air made it where vehicle exhaust was visible, that the air behind certain vehicles is very violent. Awesome to see first hand that all this is true. Is there a template for the perfect boat tail design?

[California98Civic]

Originally Posted by Sentraguy

I noticed today as the cold air made it where vehicle exhaust was visible, that the air behind certain vehicles is very violent. Awesome to see first hand that all this is true. Is there a template for the perfect boat tail design?

Check this link for starters: http://ecomodder.com/forum/showthrea...tml#post116392